The present invention relates to a Ni—Pt alloy superior in workability, a sputtering target manufacturing by rolling a Ni—Pt alloy ingot, and a manufacturing method of such Ni—Pt alloy and Ni—Pt alloy target.
Ni—Pt is used as a sputtering target for semiconductor devices, and this Ni—Pt target was conventionally manufactured with a powder metallurgy process. In other words, the target was manufactured by sintering Ni powder and Pt powder, or by sintering Ni—Pt alloy powder.
Since it is impossible for a sintered product to become a 100% high density product, it is undeniable that such sintered product is inferior in terms of density in comparison to a target manufactured via melting, casting and rolling.
Therefore, gas components easily get mixed into the target, and not only does this reduce purity, it causes abnormal electrical discharge during sputtering, induces the generation of particles, and deteriorates the deposition characteristics.
Meanwhile, a Ni—Pt product formed via melting and casting has a problem in that it is extremely hard and brittle. As a result, when a Ni—Pt ingot is rolled, there is a problem in that grain boundary fractures occur, and it is not possible to manufacture a flat and even planar target. This is the reason targets were manufactured with the powder metallurgy process as described above.
In light of the foregoing circumstances, a Ni—Pt target formed via melting and casting, and which is free from cracks, has been proposed. For instance, refer to Japanese Patent Laid-Open Publication No. S63-33563.
Japanese Patent Laid-Open Publication No. S63-33563 considered the cause of fractures to be the coarsened crystal grains in the target and, in order to obtain fine crystal grains, attempted to inhibit the coarsening of crystals by preparing a mold with large heat capacity or a water-cooled mold, and performing rapid quenching by inhibiting the temperature rise of the mold.
Nevertheless, with Japanese Patent Laid-Open Publication No. S63-33563, there is a drawback in that large equipment is necessary for preparing a mold with large heat capacity or a water-cooled mold, and there is a problem in that it is difficult to inhibit the coarsening of crystals unless the cooling speed is considerably fast.
Further, the crystals that come in contact with the mold are fine, and become coarse as they draw away from such mold. Thus, there is a problem in that it is difficult to obtain a uniform crystal structure, and it is therefore not possible to manufacture a target having a uniform structure or that is stable.